Abstract
A partial clone of caldesmon, coding for the C-terminal 288 amino acids, was isolated from a human fetal liver cDNA library and sequenced. Expression of the clone in Escherichia coli produced a peptide called H1 (M(r) 32,549), which inhibited tropomyosin-enhanced actomyosin Mg(2+)-ATPase activity by 90% with half maximal inhibition at 0.03-0.04 mol H1 per mol actin. The inhibition could be reversed by Ca(2+)-calmodulin. H1 bound actin, Ca(2+)-calmodulin and tropomyosin and smooth muscle myosin with high affinities. This latter finding shows the presence of a second myosin-binding site in caldesmon. This was confirmed in thrombic digests of native sheep aorta and chicken gizzard caldesmon.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Actins / pharmacology
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Actomyosin / antagonists & inhibitors
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Amino Acid Sequence
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Animals
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Binding Sites
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Ca(2+) Mg(2+)-ATPase / antagonists & inhibitors
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Calcium / metabolism
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Calmodulin / metabolism
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Calmodulin-Binding Proteins / chemistry
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Calmodulin-Binding Proteins / metabolism*
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Calmodulin-Binding Proteins / pharmacology
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Chickens / genetics
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Cloning, Molecular
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DNA, Complementary / genetics
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Humans
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Liver / chemistry
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Molecular Sequence Data
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Muscle, Smooth / chemistry
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Myosins / metabolism*
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Myosins / pharmacology
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Organ Specificity
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Peptide Fragments / metabolism
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Peptide Fragments / pharmacology
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Recombinant Fusion Proteins / metabolism
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Recombinant Fusion Proteins / pharmacology
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Sequence Alignment
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Sequence Homology, Amino Acid
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Sheep
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Species Specificity
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Tropomyosin / antagonists & inhibitors
Substances
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Actins
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Calmodulin
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Calmodulin-Binding Proteins
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DNA, Complementary
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Peptide Fragments
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Recombinant Fusion Proteins
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Tropomyosin
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Actomyosin
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Ca(2+) Mg(2+)-ATPase
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Myosins
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Calcium